Delayed graft function in kidney transplantation

Delayed graft function is a form of acute renal failure resulting in post-transplantation oliguria, increased allograft immunogenicity and risk of acute rejection episodes, and decreased long-term survival. Factors related to the donor and prerenal, renal, or postrenal transplant factors related to the recipient can contribute to this condition. From experimental studies, we have learnt that both ischaemia and reinstitution of blood flow in ischaemically damaged kidneys after hypothermic preservation activate a complex sequence of events that sustain renal injury and play a pivotal part in the development of delayed graft function. Elucidation of the pathophysiology of renal ischaemia and reperfusion injury has contributed to the development of strategies to decrease the rate of delayed graft function, focusing on donor management, organ procurement and preservation techniques, recipient fluid management, and pharmacological agents (vasodilators, antioxidants, anti-inflammatory agents). Several new drugs show promise in animal studies in preventing or ameliorating ischaemia-reperfusion injury and possibly delayed graft function, but definitive clinical trials are lacking. The goal of monotherapy for the prevention or treatment of is perhaps unattainable, and multidrug approaches or single drug targeting multiple signals will be the next step to reduce post-transplantation injury and delayed graft function.

The significance of the anti-class I antibody response. I. Clinical and pathologic features of anti-class I-mediated rejection

In renal transplantation, preformed cytotoxic antibody against donor HLA class I antigens causes hyperacute rejection of renal allografts, but its pathogenic significance when it develops in the posttransplant period is unknown. In the present studies we describe the clinical and pathologic features of patients with rejection associated with anti-class I. In the course of 400 consecutive cadaveric renal transplants, 7 patients were identified who had antibody against donor class I HLA antigens in association with atypical but distinctive patterns of rejection. All 7 were presensitized. In 3 patients, the transplant had been inadvertently performed with a positive donor-specific T cell crossmatch. In the remaining 4, the T cell crossmatch on current sera was negative but became positive posttransplant. The clinical picture was deterioration of graft function with rapid onset of oliguria, apparently due to acute tubular necrosis, but with persistence of blood flow demonstrable by radioisotope scan studies. Renal histology showed that the typical lesions observed in cell-mediated rejection, such as tubulitis and interstitial infiltration, were absent. Granular complement deposition (6), polymorphonuclear infiltration (6), and endothelial injury in the microvasculature (6) were common, and mononuclear infiltrates were absent (2) or not prominent (4). In 3 patients the glomerular changes resembled a picture of hemolytic uremic syndrome, with capillary fibrin thrombi and widening of the subendothelial space. IgG staining was negative. The pathologic features suggest that anti-class I antibody appearing or persisting in the early posttransplant period injures the endothelium of the microvasculature, with the clinical presentation different from that of hyperacute rejection. Particularly in sensitized patients, rapid deterioration in function, leading to a picture of acute tubular necrosis, with pathologic features of endothelial injury in the microcirculation, should suggest the diagnosis of anti-class I-mediated rejection.

Atrial natriuretic factor in oliguric acute renal failure. Anaritide Acute Renal Failure Study Group

Atrial natriuretic peptide (ANP), an endogenous hormone synthesized by the cardiac atria, has been shown to improve renal function in multiple animal models of acute renal failure. In a recent multicenter clinical trial of 504 patients with acute tubular necrosis (oliguric and nonoliguric), ANP decreased the need for dialysis only in the oliguric patients. In the present study, 222 patients with oliguric acute renal failure were enrolled into a multicenter, randomized, double-blind, placebo-controlled trial designed to assess prospectively the safety and efficacy of ANP compared with placebo. Subjects were randomized to treatment with a 24-hour infusion of ANP (anaritide, 0.2 microgram/kg/min; synthetic form of human ANP) or placebo. Dialysis and mortality status were followed up for 60 days. The primary efficacy end point was dialysis-free survival through day 21. Dialysis-free survival rates were 21% in the ANP group and 15% in the placebo group (P = 0.22). By day 14 of the study, 64% and 77% of the ANP and placebo groups had undergone dialysis, respectively (P = 0.054), and 9 additional patients (7 patients, ANP group; 2 patients, placebo group) needed dialysis but did not receive it. Although a trend was present, there was no statistically significant beneficial effect of ANP in dialysis-free survival or reduction in dialysis in these subjects with oliguric acute renal failure. Mortality rates through day 60 were 60% versus 56% in the ANP and placebo groups, respectively (P = 0.541). One hundred two of 108 (95%) versus 63 of 114 (55%) patients in the ANP and placebo groups had systolic blood pressures less than 90 mm Hg during the study-drug infusion (P < 0.001). The maximal absolute decrease in systolic blood pressure was significantly greater in the anaritide group than placebo group (33.6 versus 23.9 mm Hg; P < 0.001). This well-characterized population with oliguric acute renal failure had an overall high morbidity and mortality.

Acute renal failure. II. Experimental models of acute renal failure: imperfect but indispensable

Acute renal failure (ARF) due to ischemic or toxic renal injury, a clinical syndrome traditionally referred to as acute tubular necrosis (ATN), is a common disease with a high overall mortality of approximately 50%. Little progress has been made since the advent of dialysis more than 30 years ago in improving this outcome. During this same period, a considerable amount of basic research has been devoted to elucidating the pathophysiology of ATN. The ultimate goal of this research is to facilitate the development of therapeutic interventions that either prevent ARF, ameliorate the severity of tubular injury following an acute ischemic or toxic renal insult, or accelerate the recovery of established ATN. This research endeavor has been highly successful in elucidating many vascular and tubular abnormalities that are likely to be involved in ischemic and toxic ARF. This information has led to impressive advances in the development of a number of different pharmacological interventions that are highly effective in ameliorating the renal dysfunction in animal models of ARF. Although these developments are exciting and promising, enthusiasm of investigators involved in this endeavor has been tempered somewhat by the results of a few recent clinical studies of patients with ATN. These trials, designed to examine the efficacy in humans of some of the interventions effective in animal models of ARF, have resulted in little or no benefit. This is therefore an important time to reevaluate the approaches we have taken over the past three to four decades to develop new and effective treatments for ATN in humans. The major goals of this review are 1) to evaluate the relevance and utility of the experimental models currently available to study ischemic and toxic renal injury, 2) to suggest novel experimental approaches and models that have the potential to provide advantages over methods currently available, 3) to discuss ways of integrating results obtained from different experimental models of acute renal injury and of evaluating the relevance of these findings to ATN in humans, and 4) to discuss the difficulties inherent in clinical studies of ATN and to suggest how studies should be best designed to overcome these problems.

Acute renal tubular necrosis and death of mice orally infected with Escherichia coli strains that produce Shiga-like toxin type II

Escherichia coli O157:H7 strains have been implicated as etiologic agents in food-borne outbreaks of hemorrhagic colitis and the hemolytic-uremic syndrome. A prototype E. coli O157:H7 strain, designated 933, produces Shiga-like toxin I (SLT-I) and SLT-II and harbors a 60-MDa plasmid. In a previous study, streptomycin-treated mice were fed 933 together with a derivative cured of the 60-MDa plasmid (designated 933cu). Strain 933cu colonized poorly, but in approximately one-third of the animals, an isolate of 933cu was obtained from the feces that had regained the ability to colonize well. This isolate, designated 933cu-rev, killed all of the animals when fed alone to mice. In this investigation, two types of experiments were done to assess whether SLT-I, SLT-II, or both contributed to the death of mice fed 933cu-rev. (i) Mice were pretreated with monoclonal antibodies to SLT-I, SLT-II, SLT-I and SLT-II, or cholera toxin (as a control) before infection with 933cu-rev. (ii) Mice were fed either an E. coli K-12 strain carrying cloned SLT-I genes or the same K-12 strain carrying cloned SLT-II genes. The results of both types of experiments indicated that the deaths of the orally infected mice were due solely to SLT-II. Extensive histological and selected electron microscopic examinations of various tissues from the infected animals suggested that death was due to acute renal cortical tubular necrosis consistent with toxic renal damage. These data indicate a critical role for SLT-II, but not SLT-I, in renal damage associated with E. coli O157:H7 infection of streptomycin-treated mice.

Mechanical ventilation and acute renal failure

OBJECTIVE

To review the current literature on possible mechanisms by which mechanical ventilation may initiate or aggravate acute renal failure.

DATA SOURCE

A Medline database and references from identified articles were used to perform a literature search relating to mechanical ventilation and acute renal failure.

DATA SYNTHESIS

Acute renal failure may be initiated or aggravated by mechanical ventilation through three different mechanisms. First, strategies such as permissive hypercapnia or permissive hypoxemia may compromise renal blood flow. Second, through effects on cardiac output, mechanical ventilation affects systemic and renal hemodynamics. Third, mechanical ventilation may cause biotrauma-a pulmonary inflammatory reaction that may generate systemic release of inflammatory mediators. The harmful effects of mechanical ventilation may become more significant when a comorbidity is present. In these situations, it is more difficult to maintain normal gas exchange, and moderate arterial hypoxemia and hypercapnia are often accepted. Renal blood flow is compromised due to a decreased cardiac output as a consequence of high intrathoracic pressures. Furthermore, the effects of biotrauma are not limited to the lungs but may lead to a systemic inflammatory reaction.

CONCLUSIONS

The development of acute renal failure during mechanical ventilation likely represents a multifactorial process that may become more important in the presence of comorbidities. Development of optimal interventional strategies requires an understanding of physiologic principles and greater insight into the precise molecular and cellular mechanisms that may also play a role.

Role of Oxidative Stress in Drug-Induced Kidney Injury

The kidney plays a primary role in maintaining homeostasis and detoxification of numerous hydrophilic xenobiotics as well as endogenous compounds. Because the kidney is exposed to a larger proportion and higher concentration of drugs and toxins than other organs through the secretion of ionic drugs by tubular organic ion transporters across the luminal membranes of renal tubular epithelial cells, and through the reabsorption of filtered toxins into the lumen of the tubule, these cells are at greater risk for injury. In fact, drug-induced kidney injury is a serious problem in clinical practice and accounts for roughly 20% of cases of acute kidney injury (AKI) among hospitalized patients. Therefore, its early detection is becoming more important. Usually, drug-induced AKI consists of two patterns of renal injury: acute tubular necrosis (ATN) and acute interstitial nephritis (AIN). Whereas AIN develops from medications that incite an allergic reaction, ATN develops from direct toxicity on tubular epithelial cells. Among several cellular mechanisms underlying ATN, oxidative stress plays an important role in progression to ATN by activation of inflammatory response via proinflammatory cytokine release and inflammatory cell accumulation in tissues. This review provides an overview of drugs associated with AKI, the role of oxidative stress in drug-induced AKI, and a biomarker for drug-induced AKI focusing on oxidative stress.

Rhabdomyolysis and shock after intravenous amphetamine administration

Five patients who had injected intravenous (i.v.) phenmetrazine or methamphetamine developed marked prostration resembling septic shock, disseminated intravascular coagulation, rhabdomyolysis with myoglobinuria, and azotemia. Soon after injection, four noted chills, fever, sweats, nausea, and abdominal cramps. Within hours, they developed vomiting, myalgias, paresthesias, headache, and orthostasis. Cardiorespiratory arrest, accelerated bleeding, and noncardiac pulmonary edema were observed in one patient. From 4 to 11 litres of saline were required in the first 24 h to maintain blood pressure and urine output, suggesting that shock resulted from massive loss of intravascular volume into necrotic muscle. Recognition of this syndrome and treatment by aggressive volume replacement led to the recovery of all five patients.

The "stuck twin" phenomenon: ultrasonographic findings, pregnancy outcome, and management with serial amniocenteses

Thirteen consecutive twin pregnancies affected by the "stuck twin" phenomenon were reviewed to determine the potential benefit of serial amniocenteses. The fetal survival rate for the eight pregnancies that underwent serial amniocenteses was 69% (11 of 16 fetuses). This is significantly improved compared with a fetal survival rate of 20% among the five preceding pregnancies managed without serial amniocenteses at the same institution (p = 0.01). It is also markedly improved compared with a combined fetal survival rate of 16% among 48 previously reported pregnancies with the stuck twin phenomenon managed without serial amniocenteses (p less than 0.0001). Survival correlated with the absence of concomitant pregnancy complications (i.e., maternal hypertension or intractable labor) and with the absence of severe fetal structural abnormalities. Procedural complications occurred in three of eight pregnancies (37.5%) managed with serial amniocenteses and was attributed as a cause of fetal death in one case. Two of 11 survivors (18%) had complications after serial amniocenteses including brain infarction and renal tubular necrosis. Serial amniocenteses may significantly improve the survival rate of twin gestations affected by the stuck twin phenomenon but may be associated with complications among survivors.

Herbs and the kidney

The use of herbal therapy has increased dramatically in past years and may lead to renal injury or various toxic insults, especially in renal patients. In most countries, herbal products are not regulated as medicines. Herbal poisoning may be secondary to the presence of undisclosed drugs or heavy metals, interaction with the pharmacokinetic profile of concomitantly administered drugs, or association with a misidentified herbal species. Various renal syndromes were reported after the use of medicinal plants, including tubular necrosis, acute interstitial nephritis, Fanconi's syndrome, hypokalemia or hyperkalemia, hypertension, papillary necrosis, chronic interstitial nephritis, nephrolithiasis, urinary retention, and cancer of the urinary tract. It seems critical that caregivers be aware of the potential risk of such often underreported therapy and carefully question their patients about their use of this popular branch of alternative medicine.

Renal failure in fulminant hepatic failure and terminal cirrhosis: a comparison between incidence, types, and prognosis

Forty patients with terminal cirrhosis and 40 patients with fulminant hepatic failure-all consecutively admitted-were studied with regard to incidence, types, and prognosis of complicating renal insufficiency. Renal failure was considered present when the serum creatinine was greater than 0.20 mmol/l. Of the patients with cirrhosis 26 (65%) developed renal failure. In 15 the type was functional, in three due to acute tubular necrosis, and in eight indeterminable. Of the patients with fulminant hepatic failure 22 (55%) had renal insufficiency; of these 13 had functional renal failure, five acute tubular necrosis, and in four the type was indeterminable. In both categories of patients, renal failure was equally frequent among patients with or without gastrointestinal bleeding and with or without ascites or diuretic therapy. The biochemical tests of liver function were similar in patients with or without renal failure in both categories. The mean renal blood flow in seven unselected patients with fulminant hepatic failure was reduced in the same order as previously observed in patients with cirrhosis. In terminal cirrhosis the mortality rate was 88% in the presence of renal failure, 71% in its absence (p greater than 0.05), while the same figures in fulminant hepatic failure were 100% and 67% (p less than 0.05). The incidence, relative frequency, and prognosis of renal failure were not different in the two conditions, indicating identical pathophysiological circumstances.

Renal pathologic spectrum in an autopsy series of patients with plasma cell dyscrasia

CONTEXT

Renal dysfunction in plasma cell dyscrasias is common. It is the second most common cause of death in patients with myeloma.

OBJECTIVE

We evaluated 77 sequential autopsies performed on patients dying from complications of plasma cell dyscrasias during an 11-year period at the University of Arkansas for Medical Sciences. These consisted of 15% of all the autopsies performed during this time.

DESIGN

The kidneys were evaluated by light microscopy using hematoxylin-eosin-stained sections as well as Congo red and thioflavin T stains when amyloidosis was in the differential diagnosis. Immunofluorescence was performed on selected cases.

RESULTS

The most common lesion identified was cast nephropathy (30%). Other findings included acute tubulopathy, AL-amyloidosis, light chain deposition disease, tubulointerstitial nephritis associated with monotypic light chain deposits, thrombotic microangiopathy, renal infarction, fungal infection, and plasma cell tumor nodules. Autolysis, an expected finding in autopsy evaluations, was significant in 25 cases.

CONCLUSIONS

Renal lesions are heterogeneous in these patients. In some cases, combined pathologic lesions were noted. Myeloma cast nephropathy predominated among all the renal lesions noted.

Endothelin up-regulation and localization following renal ischemia and reperfusion

BACKGROUND

Endothelin (ET), a potent vasoconstrictor, is known to play a role in ischemic acute renal failure. Although preproET-1 (ppET-1) mRNA is known to be up-regulated following ischemia/reperfusion injury, it has not been determined which component of the injury (ischemia or reperfusion) leads to initial gene up-regulation. Likewise, although ET-1 peptide expression has been localized in the normal kidney, its expression pattern in the ischemic kidney has not been determined. Therefore, the purpose of this study was twofold: (a) to determine whether ischemia alone or ischemia plus reperfusion is required for the up-regulation of ppET-1 mRNA to occur, and (b) to localize ET-1 peptide expression following ischemia in the rat kidney to clarify better the role of ET in the pathophysiology of ischemia-induced acute renal failure.

METHODS

Male Lewis rats underwent clamping of the right renal vascular pedicle for either 30 minutes of ischemia (group 1), 60 minutes of ischemia (group 2), 30 minutes of ischemia followed by 30 minutes of reperfusion (group 3), or 60 minutes of ischemia followed by three hours of reperfusion (group 4). The contralateral kidney acted as a control. ppET-1 mRNA up-regulation and ET-1 peptide expression were examined using the reverse transcription-polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

Reverse transcription-polymerase chain reaction yielded a control (nonischemic) value of 0.6 +/- 0.2 densitometric units (DU) of ppET-1 mRNA in the kidney. Group 1 levels (30 min of ischemia alone) were 1.8 +/- 0.4 DU, a threefold increase (P < 0.05). Group 2 levels (60 min of ischemia alone) increased almost six times above baseline, 3.5 +/- 0.2 DU (P < 0.01), whereas both group 3 and group 4 (ischemia plus reperfusion) did not experience any further significant increases in mRNA levels (1.9 +/- 0.4 DU and 2.8 +/- 0.6 DU, respectively) beyond levels in group 1 or 2 animals subjected to similar ischemic periods. ET-1 peptide expression in the ischemic kidneys was significantly increased over controls and was clearly localized to the endothelium of the peritubular capillary network of the kidney.

CONCLUSIONS

Initial ET-1 gene up-regulation in the kidney occurs secondary to ischemia, but reperfusion most likely contributes to sustaining this up-regulation. The marked increase of ET-1 in the peritubular capillary network suggests that ET-induced vasoconstriction may have a pathophysiological role in ischemic acute tubular necrosis.

Primary acute renal failure ("acute tubular necrosis") in the transplanted kidney: morphology and pathogenesis

"Acute tubular necrosis" (ATN) in the transplanted kidney, when properly differentiated from other causes of acute renal failure, appears to be a relatively benign condition. It has been widely assumed to be pathologically identical to ATN in the native kidney, but its histopathologic features have not been studied in detail. Because immunosuppressive therapy with cyclosporine adds an additional layer of complexity to the morphologic changes observed, in the present study we have confined our observations to patients immunosuppressed with steroids and azathioprine. Thirteen renal allograft biopsies from patients with ATN and 5 biopsies from patients with normal allograft function were compared with the previously obtained series of 57 native kidney ATN biopsies and 20 control biopsies. Both qualitative and quantitative differences between transplant and native kidney ATN were found. Compared with native kidney ATN, transplant ATN showed significantly less thinning and absence of proximal tubular brush border and less variation in size and shape of cells in individual tubular cross-sections. There were also significantly fewer casts and less dilatation of Bowman's space and a significantly greater number of polarizable crystals presumed to be oxalate in transplant ATN. In native kidney ATN the tubular injury sites were mostly characterized by desquamation of individual epithelial cells leaving areas of bare basement membrane (the "non-replacement" phenomenon). In transplant ATN, sites of tubular injury, although rare and affecting only short tubular segments, were characterized by the actual presence of identifiable necrotic tubular cells, a finding seldom seen in native kidney ATN. There also was a greater interstitial infiltrate of mononuclear inflammatory cells in transplant ATN compared to native kidney ATN. Electron microscopic studies of 9 transplant ATN biopsies showed a mild reduction in proximal tubular brush border compared with controls but this alteration was significantly less than that observed in native kidney ATN. There was no significant alteration in proximal or distal basolateral infoldings and this contrasted sharply with the marked reduction in basolateral infoldings of the plasma membrane observed in native kidney ATN. Disintegrated necrotic cells were found by electron microscopy in transplant ATN whereas these were not observed in native kidney ATN. There were significantly more cells with apoptosis (shrinkage necrosis) in transplant ATN than in native kidney ATN. There were significantly more cells with apoptosis (shrinkage necrosis) in transplant ATN than in native kidney ATN. On the other hand, there were significantly greater numbers of "non-replacement" sites in the distal tubules in native kidney ATN compared to transplant ATN.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of pressure in angiotensin II-induced renal injury: chronic servo-control of renal perfusion pressure in rats

Renal perfusion pressure was servo-controlled chronically in rats to quantify the relative contribution of elevated arterial pressure versus angiotensin II (Ang II) on the induction of renal injury in Ang II-induced hypertension. Sprague-Dawley rats fed a 4% salt diet were administered Ang II for 14 days (25 ng/kg per minute IV; saline only for sham rats), and the renal perfusion pressure to the left kidney was continuously servo-controlled to maintain a normal pressure in that kidney throughout the period of hypertension. An aortic occluder was implanted around the aorta between the two renal arteries and carotid and femoral arterial pressure were measured continuously throughout the experiment to determine uncontrolled and controlled renal perfusion pressure, respectively. Renal perfusion pressure of uncontrolled, controlled, and sham kidneys over the period of Ang II or saline infusion averaged 152.6+/-7.0, 117.4+/-3.5, and 110.7+/-2.2 mm Hg, respectively. The high-pressure uncontrolled kidneys exhibited tubular necrosis and interstitial fibrosis, especially prominent in the outer medullary region. Regional glomerular sclerosis and interlobular artery injury were also pronounced. Controlled kidneys were significantly protected from interlobular artery injury, juxtamedullary glomeruli injury, tubular necrosis, and interstitial fibrosis as determined by comparing the level of injury. Glomerular injury was not prevented in the outer cortex. Transforming growth factor (TGF)-beta and active NF-kappaB proteins determined by immunohistochemistry were colocalized in the uncontrolled kidney in regions of interstitial fibrosis. We conclude that the preferential juxtamedullary injury found in Ang II hypertension is largely induced by pressure and is probably mediated through the TGF-beta and NF-kappaB pathway.

Apoptosis and cell desquamation in repair process of ischemic tubular necrosis

To elucidate the role of apoptosis and cell desquamation in the repair phase of acute tubular necrosis, morphological findings after 60 min ischaemia were investigated in rats. A morphometric analysis of the cell proliferation and of the epithelial cellularity of reconstructing tubules was performed. The kinetics of apoptosis and cell desquamation were also examined. Ischaemia and reperfusion injury resulted in widespread necrosis of tubules at day 1. Subsequently, a regenerative epithelial hyperplasia took place in the early stage. The most marked increase in cellularity in the damaged tubules was on day 6, when the tubules became lined by hyperplastic epithelial cells with papillary clusters. The number of papillary clusters decrease up to day 8, and during this period many desquamated cells from the clusters were observed in the tubular lumen. In the later stage, hyperplastic epithelial cells were reduced to their original cellularity and during this period the number of apoptotic cells obviously increased, while the damaged tubules were reconstructed. We conclude that epithelial overproduction occurs in the early phase after tubular necrosis, and excess hyperplastic epithelial cells regress during the repair process by cell desquamation and apoptosis, both of which are essential for the recovery of the original tubular structure.

Fenoldopam Mesylate in Early Acute Tubular Necrosis: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Acute tubular necrosis (ATN) occurs commonly in critically ill patients and is associated with increased morbidity and mortality. Fenoldopam is a dopamine receptor alpha1-specific agonist that increases renal blood flow in patients with kidney failure. We hypothesized that administration of low-dose fenoldopam during early ATN would decrease the need for dialysis therapy and/or incidence of death at 21 days.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled, clinical trial in 155 patients with early ATN. Patients were considered eligible for enrollment if serum creatinine level increased to 50% greater than admission levels within 24 hours and mean arterial pressure was greater than 70 mm Hg. Patients were randomly assigned to the administration of placebo or fenoldopam for 72 hours.

RESULTS

Overall, 22 of 80 patients (27.5%) in the fenoldopam group reached the primary end point compared with 29 of 75 patients (38.7%) in the placebo group (P = 0.235). This 11% absolute reduction in the primary end point was not statistically significant (P = 0.23). Similarly, there was no difference in the incidence of dialysis therapy between patients randomly assigned to fenoldopam (13 of 80 patients; 16.25%) versus the placebo group (19 of 75 patients; 25.3%; P = 0.163). Moreover, there was no statistically significant difference in 21-day mortality rates between the 2 groups (fenoldopam, 13.8% versus placebo, 25.3%; P = 0.068). In secondary analyses, fenoldopam tended to reduce the primary end point in patients without diabetes and postoperative cardiothoracic surgery patients with early ATN (fenoldopam patients without diabetes, 14 of 54 patients [25.9%] versus placebo patients without diabetes, 23 of 52 patients [44.2%]; P = 0.048) and postoperative cardiothoracic patients (6 of 34 patients [17.6%] versus 14 of 36 patients [38.8%]; P = 0.049). Conversely, fenoldopam did not improve the primary end point in patients with diabetes or those with acute renal failure from other causes. A larger multicenter trial using separate randomizations for patients with and without diabetes will be needed to determine the efficacy of fenoldopam mesylate in specific subpopulations with ATN.

CONCLUSION

Fenoldopam does not reduce the incidence of death or dialysis therapy in intensive care unit patients with early ATN.

Vascular complications after live donor renal transplantation: study of risk factors and effects on graft and patient survival

We evaluated the incidence and management of vascular complications after live donor renal transplantation. Possible risk factors and their effects on patient and graft survival were also assessed.

MATERIALS AND METHODS

A total of 1,200 consecutive live donor renal transplants were performed in 1,152 patients at a single institution. The incidence of different types of vascular complications were determined and correlated with relevant risk factors. The impact on patient and graft survival was also studied.

RESULTS

There were 34 vascular complications (2.8%). Stenotic or thrombotic complications were recorded in 11 cases (0.9%), including renal artery stenosis in 5 (0.4%), renal artery thrombosis in 5 (0.4%) and renal vein thrombosis in 1 (0.1%). Hemorrhagic complications were observed in 23 patients (1.9%). Although no risk factors could be identified that were related to stenotic or thrombotic complications, grafts with multiple renal arteries were significantly associated with hemorrhagic complications (p = 0.04). Stenotic and thrombotic complications as well as hemorrhagic complications were significantly associated with subsequent biopsy proved acute tubular necrosis (p <0.001). The mean 5-year patient and graft survival rates +/- SD for those with vascular complications were 71.9% +/- 1.9% and 41.6% +/- 8.9% compared with 86.3% +/- 1.1% and 76.8% +/- 1.4% for the remainder of our transplant population, respectively (p <0.001). The deleterious impact on survival was not only observed in recipients with thrombotic or stenotic crises, but also in those with hemorrhagic sequelae.

CONCLUSIONS

Hemorrhagic crises are as serious as the stenotic and thrombotic complications affecting patient and graft survival. Because they are a significant factor in the development of hemorrhagic complications, grafts with multiple renal arteries should be managed critically.

Ischaemia-reperfusion injury in the rat kidney: the effect of preconditioning

OBJECTIVES

To design and establish a model to examine whether brief periods of renal artery occlusion (ischaemic preconditioning, IP) confers protection from the effects of a subsequent period of ischaemia and reperfusion of the rat kidney.

MATERIALS AND METHODS

Ninety rats were randomized into six groups, i.e. sham-operated controls; IP alone; a 20 or 40 min period of left renal ischaemia (RI) alone; and IP followed by a 20 or 40 min period of RI. Preconditioning involved the sequential clamping of the left renal artery for 4 min and its release for 11 min, a total of four times, a 'critical interval' of 30 min before the ischaemic insult. Left renal tissue integrity was determined by dimercapto-succinic acid (DMSA) radionuclide imaging on a gamma-camera both immediately (day 0) and 2 and 9 days later. Acute tubular necrosis was also assessed histologically.

RESULTS

RI for 20 min resulted in a significant decrease in left renal tissue integrity on day 2 only (P < 0.001), whereas RI for 40 min caused significant left renal dysfunction on day 0, day 2 and day 9 (P < or = 0.01). For a given duration of ischaemia, there was no significant difference between results from (IP + RI) rats compared with RI-only rats at any of the three times. There was no significant alteration in renal tissue integrity in the IP-only rats compared with sham-operated controls. Histological findings paralleled the data obtained from DMSA uptake.

CONCLUSIONS

The IP regimen and 30 min 'critical interval' confers no protection to the kidney from a 20 or 40 min ischaemic episode. The IP regimen itself appears to have no effect, confirming the validity of our experimental model.

Maximal hydration during anesthesia increases pulmonary arterial pressures and improves early function of human renal transplants

The recipient's hemodynamic condition during anesthesia for renal transplantation has a major influence on the early diuresis of the graft. The effect of maximal hydration during operation was studied in a series of 120 primary human cadaver kidney transplantations performed under peroperative monitoring of the pulmonary arterial pressures (PAPs). The PAPs levels before and at the time of clamp release were correlated with the frequency of postoperative acute tubular necrosis (ATN). The 120 patients were divided in two groups according to the PAPs levels before release of the vascular clamps: group 1 (22 patients) with a mean PAP (PAP) of less than or equal to 20 mm Hg and a diastolic PAP (DPAP) of less than or equal to 15 mm Hg was compared with group 2 (98 patients) with a PAP of greater than 20 mm Hg and a DPAP of greater than 15 mm Hg. Both groups were comparable with regard to the donor's data and the quantity of peroperative fluids. The frequency of ATN was 36% in group 1 versus only 6% in group 2. This difference is attributed to the different hemodynamic conditions in both groups: at the beginning of the transplant procedure, PAP, DPAP, and central venous pressure (CVP) were higher in group 2; at the time of clamp release, PAP, DPAP, CVP, and systolic blood pressure (SBP) were also higher in group 2. This study emphasizes the importance of the PAPs levels at the time of release of vascular clamps to avoid postoperative ATN of a kidney transplant.

Renal decapsulation in the prevention of post-ischemic oliguria

The delayed onset of anuria/oliguria in acute tubular necrosis has been theorized to represent a complicating compartment syndrome, i.e., parenchymal swelling within an unyielding capsule. To test this proposition, 12 monkeys had suprarenal aortic cross-clamping, followed by unilateral renal decapsulation to create an experimental as well as a control kidney unit in the same animal. Histologic examination uniformly confirmed tubular necrosis at death or sacrifice. Subsequent split renal function studies (creatinine, urea, and free water clearances) indicated significantly greater maintenance of renal function by the decapsulated kidney than by its paired control. Clinical evaluation in 21 hemorrhagic shock patients, with the capsule of one kidney stripped, revealed on follow-up that 15 developed a renal failure consistent with acute tubular necrosis. Although three patients with polyuric failure died before split studies could be run and two others have been too recent for computer analysis to have been completed, nine of the remaining ten had significantly greater renal plasma flows (194 versus 121 ml/min M(2), p < .01) and significantly greater urine flows (.99 versus .18 ml/min M(2), p < .01) on the decapsulated side than on the control, as determined by differential renal scans. No significant difference in these same lateralized renal functions was noted in the tenth patient with renal failure and in the six survivors without renal failure. Renal decapsulation as prophylaxis reduced the anticipated incidence of oliguria/anuria from an expected 75% to 7% (p < .01) in these 21 shock patients. Such data suggest that delayed renal ischemia, possibly based on a compartment syndrome, may be the cause for a progression of acute tubular necrosis from polyuria to oliguria and then to anuria.